Solution or bath for use in electrically preparing stencil-plates, die-plates, and the like



G. E. WERTHEIMER.

SOLUTION 0R BATH FOR USE IN ELECIRICALLY PREPARING STENCIL PLATES, DIE

PLATES, AND THE LIKE.

APPLICATION FILED MAY 16. 1918.

G Ewzrkhzlmar UNITED STATES PATENT OFFICE.

GOTTHOLD E. WERTHEIMER, OF ASTORIA, NEW YORK.

SOLUTION OR BATH FOR USE IN ELECTRICALLY PREPARING STENCIL-PLATES DIE- PLATES, AND THE LIKE.

Application filed May 16, 1918.

To all whom it may concern Be it known that I, GOTTHOLD EPHRAIM lVERTHEIMER, a subject of the Emperor of Austria, and a declarant of the United States of America, residing at 531 First avenue, Astoria, borough of Queens, in the county of Queens and State of New York, have invented certain new and useful Improved Solutions or Baths for Use in Electrically Preparing Stencil-Plates, Die- Plates, and the like, of which the following is a specification.

This invention relates to a composition of matter adapted to be used as the solution or bath in connection with a process of preparing metallic stencil plates or die plates or blocks or like articles, involving the erosion or eating away of certain parts of such plates by the use of electric current in conjunction with said solution or bath.

The object of the present invention is to provide a solution or bath which will enable said process to be expeditiously applied to annealed or hardened metals, such as steel, whereby stencil or die plates or blocks formed of such annealed or hardened metals may be rapidly produced at a low cost and with a minimum of labor.

Another object of the invention is to provide a solution or bath by the use of which the metal from the plate or block may be rapidly removed while producing a uniform and smooth surface on the remaining portion of the plate or block.

The improved solution or bath according to the present invention comprises a mixture of sulfuric and nitric acids, ammonium chlorid and water, with a small proportion .of copper nitrate. These ingredients are preferably employed in the proportions of eighty parts. of sulfuric acid, twenty parts of nitric acid, two hundred parts of ammonium chlorid, five parts of copper nitrate, and six hundred and ninety-five parts of water.

In preparing the solution, granulated ammonium chlorid is firstly dissolved in water, at approximately the boiling point in substantially the proportion of one pound of ammonium chlorid to one gallon of water. By this means a saturated solution of ammonium chlorid is obtained. The other ingredients are mixed together in substan tially the proportions stated, and the solution of ammonium chlorid prepared as de- Specification of Letters Patent.

Patented Apr. 26, 1921.

Serial No. 235,012.

scribed, in substantially the ro ortion iven above is added thereto, thg erilzire miiture belng thoroughly stirred to secure an intimate admlxture of the various ingredients.

The resultlng solution is then preferably heated to a temperature of approximately eighty-three degrees Fahrenheit, and maintainedat about that temperature during the operation of the process, by any suitable electrlcal or other means. The =s0lution may, of course, be used cold, but it is found that the best results are obtained when the same 1s kept at the temperature mentioned while the process is in operation.

The accompanying drawing diagram matically indicates the manner in which the solution may be used in the treatment of a metallic plate or block from which a stencil plate or die plate is to be prepared.

The metallic plate or block 1 to be operated on is immersed in the solution or bath 2 contalned in a suitable tank or receptacle if) and an electric current of suitable strength 1s passed through the plate or block serving asan anodeand through the solution to a suitable cathode 4, and it is found that those parts of the plate or block unprotected by a resisting coating of suitable form are very rapidlyeroded or cut away. In tests which have been made with this solution heated to the temperature above mentioned and using an electric current of about 6 or 7 volts and about 35 to 40 amperes, it has been found possible to out into annealed or hardened steel to a depth of three sixty-fourths of an inch in one hour over any desired configuration. The great utility of this solution or bath for the purpose stated will thus be readily recognized.

I have found that the addition of the copper nitrate to the other ingredients of the solution tends to reduce the erratic action of the solution on the metal and to increase the uniformity and smoothness of the surfaces produced thereon.

The inclusion of the granulated ammonium chlorid in the solution has been found I the process described in my companion application Serial No. 208558 filed December What I claim and desire to secure by Let- 5 ters Patent is:--*-

1. A solution for use in the electrolytic treatment of metallic plates or blocks, prepared by' mixing together sulfuric acid, nitric acid, ammonium chlorid and water,

10 with a small proportion of copper nitrate.

2; A-solution for use in the electrolytic treatment of metallic plates or blocks, prepared by-mixing together the following ingredients in substantially the following pro-' In testimony whereof I afiiX my signature. GOTTHOLD E. WERTHEIMER. 

